Polyvinyl amine as a modified and grafted shell for Fe3O4 nanoparticles: As a strong solid base catalyst for the synthesis of various dihydropyrano[2,3-c]pyrazole derivatives and the Knoevenagel condensation

In this work, we reported one-step deposition of polyacrylamide on nano-magnetite surface via a simple and in situ polymerization of acryl amide to form n-Fe₃O₄/PAM nanocomposite. The amide (–CONH₂) groups could be converted easily to amine (–NH₂) groups through Hofmann degradation to introduce n-Fe₃O₄/PVAm as a highly efficient heterogeneous base catalyst. The obtained organic-inorganic nanocomposite exhibited high catalytic activity for the solvent-free syntheses of various dihydropyrano[2,3-c]pyrazole derivatives and the Knoevenagel condensation in high to excellent yields and in the following, a plausible mechanism for the synthesis of them has been proposed. Because of the polymer layer coated Fe₃O₄ nanoparticles, the catalyst has many catalytic units, and acceptable thermal stability and recyclability. Titration, FT-IR, SEM, TGA, VSM, and XRD analysis were used for characterization of the catalyst. Also, the nanocomposite can be easily recovered by a magnetic field and reused up to 9 times without distinct deterioration in catalytic activity.     

H5IO6/KI: A New Combination Reagent for Iodination of Aromatic Amines,and Trimethylsilylation of Alcohols and Phenols through in situ Generation of Iodine under Mild Conditions

A simple method for the in situ generation of iodine using H₅IO₆/KI has been developed, and its application in silylation of OH group and iodination of aromatic amines is described.     

Fibroin-functionalized magnetic carbon nanotube as a green support for anchoring silver nanoparticles as a biocatalyst for A3 coupling reaction

Novel and powerful fibroin-functionalized magnetic carbon nanotube–supported silver nanoparticles (CNT–Fe₃O₄–fibroin–Ag) were successfully synthesized as a nontoxic and inexpensive biocatalyst. The structure of the organic–inorganic hybrid bionanocomposite was characterized by various techniques such as Fourier transform infrared spectroscopy, thermogravimetric analysis, energy-dispersive X-ray, field emission-scanning electron microscopy, transmission electron microscopy, X-ray diffraction, vibrating sample magnetometry, atomic absorption spectroscopy, and inductively coupled plasma-optical emission spectrometry. Then, the catalytic activity of synthesized bionanocomposite was evaluated in the three-component A³ coupling reaction under solvent-free conditions with good to excellent yields. Several propargylamine derivatives were synthesized by the reaction of different aldehydes with amines and phenylacetylene. Biodegradability, biocompatibility, availability, easy synthesis, high stability, high-throughput, cost-effectiveness, and efficient magnetic separation are some advantages of this catalyst that make it economically justified and sustainable. Moreover, the catalyst can be recycled for several runs without appreciable loss in its catalytic activity.     

Magnetic carbon nanotube as a highly stable support for the heterogenization of InCl3 and its application in the synthesis of isochromeno[4,3-c]pyrazole-5(1H)-one derivatives

In the present study, a novel magnetically retrievable catalytic system involving indium nanoparticles on magnetic carbon nanotube (Fe₃O₄-CNT-In) was synthesized and characterized using various techniques, such as Fourier transform-infrared, thermogravimetric analysis, energy-dispersive X-ray analysis, vibrating-sample magnetometry1, X-ray diffraction, field emission-scanning electron microscopy and inductively coupled plasma-optical emission spectrometry. The catalytic activity of the synthesized nanocatalyst was evaluated in green synthesis of isochromeno[4,3-c]pyrazole-5(1H)-one derivatives from the reaction of ninhydrin and arylhydrazones under solvent-free conditions. The catalyst was magnetically separated from the reaction mixture using an external magnet and recovered for five cycles without an appreciable decrease in its catalytic efficiency. Performing the reactions in environmentally friendly and affordable conditions, the low catalyst percentage, high yield of products, short reaction times, large substrate scope and easy work-up are the merits of this protocol. Furthermore, four of the synthesized isochromeno[4,3-c]pyrazole-5(1H)-one derivatives are also new.     

Magnetic nitrogen-doped carbon derived from silk cocoon biomass: a promising and sustainable support for copper

Research on Chemical Intermediates - In this study, a magnetic nitrogen-doped carbon-based copper (MNC-Cu) catalyst was fabricated so that natural silk cocoons undergo thermal processes and then...     

Nanomagnetic‐supported Sulfonic Acid: Simple and Rapid Method for the Synthesis of α,α′‐Bis‐(substituted‐benzylidene) Cycloalkanones

Nanomagnetic‐supported sulfonic acid is found to be a powerful and reusable heterogeneous catalyst for the rapid synthesis of α,α′‐bis‐(substituted‐benzylidene)cycloalkanones under conventional heating and solvent free conditions. High yield, simple work up and easy recovery of the catalyst are the most obvious advantages of this procedure.